yamaha rx-v2095 wont power on

[gregtherider]

Have you checked the output transistors? If display doestn come up not ever for a second it sound like it is in high current shutdown. I would check for shorted transistors..

 

[srinath]

OK I desoldered 1 transistor and it powered up for a few sec before shutting down.
Then I desoldered the next one and it powered up and stayed on, and I tested with headphones and it worked on 1 channel.
I am not sure what I desoldered or where it was in the circuit, I have to look it up, I was desoldering on the bottom, under the board. I'll find what I desoldered and post it in a bit.
Next step it to pull the transistors out of the other channel and put it in place of these 2 and try it and see if it still works or not. And if the audio switches sides.
Oh, I need to put that 275v cap back in now too.
Cool.
Srinath.

 

[srinath]

Looking for this ...

Hi,
Q127 it is the negative driver transistor for the speaker channel A. That it is why the micro do not allow to power on to protect the speaker A.

q127 is in the left channel main ? I have to get that board covering it up and look at that bottom board. I'll have to do it in a few days.
Cool.
Srinath.

 

[srinath]

Someone have a better schematic than I got from hifiengine ? If I magnify it big enough to read, well its too blurry I cant read it then either.
Cool.
Srinath.

 

[srinath]

I cant find a decent readable schematic, so I am going to sorta rig it first. I'll get the bad transistor out, check everything else in that circuit, and if it all is fine, I'll swap another one from the amp into its place. If nothing else blows, I'll run it a few hours and call it good.
Cool.
Srinath.

 

[srinath]

I pulled that bad chip off and put a chip from another channel. The amp didn't come on.
I am not sure what is wrong, but something else is wrong in that channel.
I'll have to look in the amp, I cant read the schematics, its too blurry at magnifications I can read.
Cool.
Srinath.

 

[tauro0221]

Hi,
Try this location to see if it is better than your.
YAMAHA RX-V2095 V2095RDS Service Manual free download, schematics, eeprom, repair info for electronics

 

[tauro0221]

Hi,
You mentioned that you remove a bad chip or a bad transistor. You need to remove Q166 and Q168 and power on the amplifier and see if it is stay ON. Those transistors are for channel SPA. This is to follow in one of the thread you mentioned that transistor Q127 looked like it is burned. I do not like to remove other channel parts to test the bad part in another channel because you may end with two bad channels.

 

[srinath]

Thanks tauro0221 for the tips on the transistors. I should remove q166 and 168 but put the 5200 transistors in and check that it stays on right ? cos with that 1 bad channel 5200 removed it will power up and stay on.
Nothing looks burnt in this amp ... the q127 was looking like it had a bad solder joint though.

The electrotanya manual is the same as the hifiengine manual though ...

Cool.
Srinath.

 

[tauro0221]

Hi,
You have 2 C5200 transistors. Which of the 2 you removed out.

 

[srinath]

There are like 8-10 of em. I had the second one from the back that I thought was bad, and replaced it with the second one from front. Much to the same effect.
I will put them back exactly back in the location they were in ... and try the parts you said.
Cool.
Srinath.

 

[tauro0221]

Hi,
Check page 23. It have the output transistors layout.

 

[srinath]

Thanks for that, I saw it on another page but page 23 is better.
OK Q168 was what I pulled first and have the amp come on.
I then took Q175 which is also a 5200 and put it in Q168 and it did not power up.

I dont think I did any harm to the amp, the amp has such a quick protect mechanism it never even comes on.

Anyway then I removed Q168 and the amp came back up.

Thanks.
Srinath.

 

[tauro0221]

Hi,
Can you read the voltage going to the base of Q166 and Q168.

 

[krishnaelc]

hi srinath check the all suply like . pri prd pdet its all are perfect your amp is on

 

[srinath]

Tarro: I should check with Q168 out of the circuit obviously, cos with it in, it wont power on at all.
Krishna: I dont understand - the amp comes on and works perfect if the Q168 transistor is removed. That Q168 is almost irrelevant, its just the fact that that is there puts that circuit in play and it doesn't like that. Pretty sure the other supplies etc in the amp is fine.

Cool.
srinath.

 

[tauro0221]

Hi,
Do not install the transistors 168 and 166. . Check the voltage at the base of the transistors. That would tell you if the drivers are OKAY. You should read about 0 to 300mv going to the bases.

 

[srinath]

Perfect tauro. I will as soon as it stops snowing ... he he ...
Cool.
Srinath.

 

[srinath]

If the transistor is lying face up (the printed side on top, metal back on bottom) and the pins are pointing toward you - left pin will be getting .41-42 volts dc, center will get .51 v dc, and right pin will get -59 vdc. I didn't look at pin outs for that transistor before I went into sub 0 weather ... he he, brain freeze has a whole new meaning now.
I think its powering on and staying on, but the safety relay still not clicking.

I'll remove 166 and try it. I didn't manage to get 166 removed. Q168 is desoldered though.

Thanks.
Srinath.

 

[srinath]

The Base location is .42v dc. 410, 420 mV. Too much ?
C is soldered to .51 vDC.
E gets -59 vDC.

Thanks.
Srinath.